Through collaboration between the City of Hope National Medical Center and the University of Minnesota, we propose to define a cohort of patients who have undergone bone marrow transplantation (BMT) at these two centers and have survived at least two years, regardless of their current life-status. The objective of this Bone Marrow Transplant Survivors' Study (BMT-SS) is to establish and characterize a cohort of 1,894 pediatric and adult long-term survivors of BMT, to address the following aims: i) Identify detailed information on the incidence and risk factors for cardiopulmonary disease, endocrine abnormalities, fertility, and subsequent cancers; ii) Describe the impact of the above complications on the quality of life in this cohort of BMT survivors; iii) Characterize the health-related behaviors and patterns of medical care in survivors. The methodology involves a mailed survey of two questionnaires: (i) the BMT-SS Questionnaire, a validated, self-administered (subjects > 18 years) or parent-administered (subjects < 18 years) questionnaire addressing all potential long-term complications in this group of survivors; and (ii) the City of Hope Quality of Life Questionnaire for Bone Marrow Transplantation (BMT-QOL), (subjects > 18 years) or the Child's Health Questionnaire (subjects < 18 years). A frequency-matched sample of 500 siblings will be enrolled into the study. The sibling controls will provide: i) the ability to make direct comparisons with the survivors, ii) data on outcomes in a noncancer population, not available from other sources (vital statistics, NHIS, etc.). For selected reported outcomes (second cancers, etc.) we will conduct additional analyses using a nested case-control approach. This will allow us to collect additional, more extensive data on survivors experiencing the outcomes (cases), and those not experiencing the outcome (controls). The cohort will be of sufficient size and heterogeneity with respect to primary malignancy, type of transplant age at transplant, and ethnic background to allow for the study of endpoints of interest in this population. The results will provide important information that may be used in the design of future therapeutic strategies and/or interventions to decrease the occurrence of deleterious effects related to treatment exposures and host factors. Having such a cohort in place will give us the opportunity in the future to continue to collect information on major study end-points (e.g., second cancers, births, cardiac complications, etc.) that may have occurred since the completion of the initial questionnaire.